What I particularly like about the article is the fact that the author conceptualizes, organizes, and interprets the research findings in the context of contemporary Cattell-Horn-Carroll (CHC) theory of intelligence....the theory I continue to advocate for as the best current psychometric taxonomy for understanding intelligence test performance.

Anyone who would like to get early access to a PDF copy of the article in EXCHANGE for a guest blog post at this blog, should contact the blogmaster at iap@earthlink.net

A body of data on IQ collected over 50 years has revealed that average population IQ varies across time, race, and nationality. An explanation for these differences may be that intelligence test performance requires literacy skills not present in all people to the same extent. In eight analyses, population mean full scale IQ and literacy scores yielded correlations ranging from .79 to .99. In cohort studies, significantly larger improvements in IQ occurred in the lower half of the IQ distribution, affecting the distribution variance and skewness in the predicted manner. In addition, three Verbal subscales on the WAIS show the largest Flynn effect sizes and all four Verbal subscales are among those showing the highest racial IQ differences. This pattern of findings supports the hypothesis that both secular and racial differences in intelligence test scores have an environmental explanation: secular and racial differences in IQ are an artifact of variation in literacy skills. These findings suggest that racial IQ distributions will converge if opportunities are equalized for different population groups to achieve the same high level of literacy skills. Social justice requires more effective implementation of policies and programs designed to eliminate inequities in IQ and literacy.

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About Me

Dr. Kevin McGrew is Director of the Institute for Applied Psychometrics (llc). Additional information, including potential conflicts of interest resulting from commercial test development or other consultation, can be found at The MindHub(TM; http://www.themindhub.com ). General email contact is iap@earthlink.net.